1. Field of the Invention
The invention relates to a device for ventilation and integrity testing of a filter unit that can be supplied with pressure and has a filter element arranged in a housing between an inlet and an outlet, wherein the housing can be ventilated by means of an air filter connected to the housing interior.
2. Description of the Related Art
A filter unit that can be supplied with pressure and has a filter element arranged in a housing between an inlet and an outlet is known from DE 43 21 927 A1. In this case, the housing can be ventilated upwards in a vertical direction by means of a hydrophobic air filter.
Although the known device has proved worthwhile in principle, it has the disadvantage that the necessary test pressure for an integrity test is supplied via the inlet line at the location of the liquid to be filtered. As a result there is a danger that the air compressed into the system for integrity testing (IT testing) of the liquid filter leads to undesirable contamination from the exterior. In order to exclude such contamination, in the filter units of the prior art a further sterile air filter is necessary, by means of which the air for the IT testing must be supplied.
Since the entire filter and line system is generally used in pre-assembled form as a closed pre-sterilized unit, this gives rise to various further disadvantages with regard to such a construction.
In the region of the inlet, for example, rigid, non-expandable pressure lines made of plastic are used instead of expandable hoses, so that precise IT testing is actually possible. Such a rigid plastic device would increase the volume of the space on the inlet side, which in turn constitutes a critical disadvantage, since as a rule high-grade liquids are to be filtered which require the least possible mixing with rinsing liquid.
The object of the present invention is to improve the known device so that unwanted contamination can be prevented cost-effectively and securely, with low expenditure on process and materials and with a small volume.